I. Field of the Invention
The present invention generally relates to the field of medical devices. More specifically, the present invention relates to support catheters or catheters that can be manipulated during deployment.
II. Related Technology
The use of intravascular devices to treat cardiovascular diseases is well known in the field of medicine. The need for a greater variety of devices to address different types of circumstances has grown tremendously as the techniques for using intravascular devices has progressed. One type of intravascular device is a catheter. Typically, an intravascular catheter is delivered into the body by first using a guide catheter that can be routed through the proper vessels in the body's vascular network in order to arrive at a site in need of a diagnostic or therapeutic technique.
Previously, support and guide catheters have been relatively simple and have been made of biocompatible plastics forming a shaft with a hollow internal lumen. The shaft is generally formed by one or more concentric tubes that are congruent to each other, where one tube typically provides support and the other tube(s) provide biocompatibility. Additionally, most guide catheters include a hub that is connected to a proximal end of the shaft in order to provide a mechanism for connecting another device, such as an inflation device or syringe. Usually, the tip of the support or guide catheter is flexible and/or shaped in order to allow for deployment and placement in the tortuous vasculature network.
In order for a medical professional to insert the catheter into the proper location in the vessel, longitudinal and rotational forces applied to the catheter must be translated to the distal end or the tip of the catheter. This enables the medical professional to maneuver the distal end of the catheter through various bends, junctions, or features of vessels in the vasculature. The tip of the catheter can be soft and flexible to prevent damage to the vasculature as the catheter is pushed or advanced therethrough. As such, the existing catheters are stiff enough to be advanced through a blood vessel, yet include the flexible tip to aid with directing the catheter through or around various bends or junctions.
There are problems, however, with the flexible distal sections used in the support catheters because too much flexibility may not allow for proper guidance of the catheters. Catheters having flexible distal ends have experienced increased instances of guide catheter “back out” during insertion or delivery of the support catheter. Guide catheters back out when a load is transmitted from a guidewire or device (e.g. support catheter, stent delivery system, PTCA balloon, etc.) to a guide catheter and the guide disengages from its preferred positioning, thereby decreasing guidewire support and creating the need for the medical professional to re-position the guiding catheter. To overcome problems associated with back out, many different support catheter tip shapes have been designed and deep seating techniques are used. These techniques are not without disadvantages, however, and may lead to vascular damage.
Additionally, many support catheters are ridged in order to prevent back out problems. However, such ridged support catheters can be traumatic to the patient's vasculature due to the rigidity being more susceptible to puncturing or otherwise damaging the inner surface of the vessel.
Certain procedures, such as valve replacements, valve repairs, and patent foramen ovale treatments in the heart, require that the treatment site be accessed by a guidewire that must pass from one side of heart to the other. After that is accomplished, a catheter device may be passed over the guidewire to access the treatment site on the second side of the heart. This requires that the guidewire pass through the septum, the wall of tissue that separates the right and left sides of a heart. The area of the septum that divides the two upper chambers is referred to as the atrial or interatrial septum and the area of the septum that divides the two lower chambers is referred to as the ventricular or interventricular septum. Puncturing the septum, however, is difficult and often leads to buckling of the guidewire.
Other procedures, such as treating arteries for disease often requires that a treatment site be accessed by a guidewire. For example, in the case of treating carotid arteries, the guidewire must travel from the aortic arch into the opening of the carotid artery (the carotid artery ostium). This passage may be complicated by the severity of the arch and the placement of the ostium. In the worst cases where difficult angles are present or other challenges exist, it may be extremely difficult to pass a guidewire. Even if guidewire access to the artery is established, it subsequently can be difficult to pass a treatment device into the artery because the difficult angles may prevent adequate support for delivery of the device, resulting in the guidewire falling out of position (or prolapse). Similar issues exist with the treatment of renal arteries, which can also be difficult to access because of the difficult angles in which they may come off the descending aorta.
It would be advantageous to have a support catheter that has the properties of flexibility and rigidity and at times when such properties are necessary. More particularly, it would be advantageous to have a support catheter that resists the temptation to backing out, buckling or prolapse under conditions where it would otherwise likely occur. In addition, it would be advantageous to have a support catheter that has these improved qualities for the purpose of puncturing a heart septum. Further, it would be advantageous to have a support catheter that has these improved qualities for the purpose of accessing difficult to reach arteries, e.g., accessing carotid or renal arteries from the aorta under difficult circumstances.